Hair bleach routinely originates as a powdery mixture of ingredients which are then transformed into a paste by mixing with water or other liquid. Hair bleach often contains active ingredients which include an oxidizing agent and an alkaline agent. These agents are often in the form of small particles and have the disadvantage of dusting. The oxidizing and alkaline agents may be harmful if ingested or inhaled; therefore it is desirable to obtain a hair bleach that does not cause this dusting.
Others have apparently attempted to control or reduce the dusting in powdered bleaching compositions. The use of materials such as paraffinic oil and/or waxes is discussed in EP 0,560,088 A1 where the patentees claim they dedust, the bleaching composition by spray application of paraffinic oils and/or waxes. Also, EP 0,583,767 A2 discusses a process for the dedusting of bleaching compositions of specified particle size by the spray application of mineral oil, silicone oil or natural oil. Additionally, U.S. Pat. Nos. 5,622,691 and 5,612,022 state that they achieve dedusting by the application of a water soluble block and/or linear random polyoxyethylene/ polyoxypropylene copolymer. French Patent No. 2,703,588 attempts dedusting by the application of a polypropylene glycol (optionally mixed with a polyalkylene glycol) in a solvent to a bleaching composition of controlled particle size, with the subsequent removal of the solvent.
EP 0,630,643 A1 discusses the spray application of molten polyethylene glycol waxes to bleaching compositions of controlled particle size, followed by subsequent grinding of the composition to eliminate agglomerations caused by the processing. Similarly, EP 0,574,696 A2 discusses a process where two dedusting agents are applied, with the first being a neutralized copolymer of methacrylic acid and methyl methacrylate and the second a water soluble cellulose derivative. None of these references, however, appears to provide a satisfactory dust free hair bleaching composition, nor do they provide a way to minimize the hair damage caused by the actual bleaching process. The methods of making such compositions are usually very process intensive.